[[Category RSC]]
Work in progress.

This page refers to .ob3, a custom format for 3D models created by Jagex. It is used by the RuneScape Classic engine since client version #74. For the earlier version of the format see [[OB2|OB2]].

<pre>public class OB3Model {

	private static final int num_seq = 0xbc614e;
	public int gouraud_shade[];
	public int vert_count;
	public int vert_x[];
	public int vert_y[];
	public int vert_z[];
	public int face_count;
	public int face_v_count[];
	public int face_v[][];
	public int face_back[];
	public int face_front[];

	public OB3Model(byte data[], int offset) {
		int vert_count = get_u_short(data, offset);
		offset += 2;
		int face_count = get_u_short(data, offset);
		offset += 2;

		vert_x = new int[vert_count];
		vert_y = new int[vert_count];
		vert_z = new int[vert_count];
		face_v_count = new int[face_count];
		faces = new int[face_count][];
		face_back = new int[face_count];
		face_front = new int[face_count];
		gouraud_shade = new int[face_count];

		for (int v = 0; v < vert_count; v++) {
			vert_x[v] = get_short(data, offset);
			offset += 2;
		}

		for (int v = 0; v < vert_count; v++) {
			vert_y[v] = get_short(data, offset);
			offset += 2;
		}

		for (int v = 0; v < vert_count; v++) {
			vert_z[v] = get_short(data, offset);
			offset += 2;
		}

		this.vert_count = vert_count;
		for (int f = 0; f < face_count; f++)
			face_v_count[f] = get_u_byte(data[offset++]);

		for (int f = 0; f < face_count; f++) {
			face_back[f] = get_short(data, offset);
			offset += 2;
			if (face_back[f] == 32767)
				face_back[f] = num_seq;
		}

		for (int f = 0; f < face_count; f++) {
			face_front[f] = get_short(data, offset);
			offset += 2;
			if (face_front[f] == 32767)
				face_front[f] = num_seq;
		}

		for (int f = 0; f < face_count; f++) {
			int i = get_u_byte(data[offset++]);
			if (i == 0)
				gouraud_shade[f] = 0;
			else
				gouraud_shade[f] = num_seq;
		}

		for (int f = 0; f < face_count; f++) {
			face_v[f] = new int[face_v_count[f]];
			for (int fv = 0; fv < face_v_count[f]; fv++) {
				if (vert_count < 256) {
					face_v[f][fv] = get_u_byte(data[offset++]);
				} else {
					face_v[f][fv] = get_u_short(data, offset);
					offset += 2;
				}
			}
		}

		this.face_count = face_count;
	}

	public static int get_u_byte(byte b) {
		return (b & 0xff);
	}

	public static int get_u_short(byte b[], int start) {
		return ((b[start] & 0xff) << 8) + (b[start + 1] & 0xff);
	}

	public static int get_short(byte b[], int start) {
		int i = get_u_byte(b[start]) * 256 + get_u_byte(b[start + 1]);
		if (i > 32767)
			i -= 0x10000;
		return i;
	}
}
</pre>

== '''Faces''' ==
A '''negative''' face_back or face_front value indicates a '''solid colour''', whereas a '''positive''' value indicates a '''texture'''. The texture is defined by its offset in the client's texture array.

When converting to/from [http://en.wikipedia.org/wiki/Wavefront_.obj_file Wavefront OBJ] format, remember that the OB3 face vertices are one less than the OBJ face vertices.

<pre>public static int decode_colour(int i) {
	i = -(i + 1);
	int r = i >> 10 & 0x1f;
	int g = i >> 5 & 0x1f;
	int b = i & 0x1f;
	return (r << 19) + (g << 11) + (b << 3);
}
</pre>

<pre>public static final int encode_colour(int r, int g, int b) {
	return -1 - (r / 8) * 1024 - (g / 8) * 32 - b / 8;
}
</pre>